Sign up to receive free email alerts when patent applications with chosen keywords are publishedSIGN UP

Abstract:

A method of manufacturing a light emitting device package, includes
following steps: providing a base which having a first surface and an
opposite second surface, and electrical structures formed on the first
surface, defining two through holes through the first and second
surfaces; mounting a light emitting element on the first surface, the
light emitting element having one pad on a top surface thereof; forming a
mask on the first surface, the mask covering the light emitting element
and defining at least one opening for exposing the at least one pad;
electrically connecting the at least one pad to the electrical structures
via at least one metal wire; filling liquid encapsulating material in a
space between the mask and the first surface to form an encapsulating
layer that encapsulating the light emitting element, the encapsulating
layer being separated from the at least one metal wire and comprising
phosphors therein.

Claims:

1. A method of manufacturing a light emitting device package, comprising
the following steps: A) providing a base, the base having a first surface
and an opposite second surface, the base defining at least two through
holes extending through the first and second surfaces, and the base
having electrical structures formed on the first surface; B) mounting a
light emitting element on the first surface of the base, the light
emitting element having at least one pad on a top surface thereof; C)
forming a mask on the first surface, the mask covering the light emitting
element and defining at least one opening for exposing the at least one
pad; D) electrically connecting the at least one pad to the electrical
structures via at least one metal wire; E) filling liquid encapsulating
material in a space between the mask and the first surface to form an
encapsulating layer that encapsulating the light emitting element, the
encapsulating layer being separated from the at least one metal wire and
comprising phosphors therein; and F) forming a cover layer on the first
surface to cover and protect the mask and the at least one metal wire.

2. The method of claim 1, further comprising a step of forming a sealing
layer on the mask for sealing the at least one opening and covering a
joint of the at least one pad and the at least one metal wire, after the
step D and before the step E.

3. The method of claim 1, further comprising a step of forming another
sealing layer on the second surface for covering the at least two through
holes.

4. The method of claim 1, further comprising a step of filling heat
conductive material in the at least two through holes.

5. The method of claim 1, wherein the cover layer is separated from the
mask and the at least one metal wire.

Description:

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This patent application is a divisional application of patent
application Ser. No. 13/172,731, filed on Jun. 29, 2011, entitled "LIGHT
EMITTING DEVICE PACKAGE AND METHOD OF MANUFACTURING THE SAME," which is
assigned to the same assignee as the present application, and which is
based on and claims priority from Chinese Patent Application No.
201010287003.X filed in China on Sep. 27, 2010. The disclosures of patent
application Ser. No. 13/172,731 and the Chinese Patent Application are
incorporated herein by reference in their entirety.

BACKGROUND

[0002] 1. Technical Field

[0003] The present disclosure relates generally to light emitting devices,
and more particularly to a package of light emitting device and a method
of manufacturing the package.

[0004] 2. Description of Related Art

[0005] Light emitting diodes (LEDs) are solid state light emitting devices
formed of semiconductors, which are more stable and reliable than other
conventional light sources such as incandescent bulbs. Thus, LEDs are
being widely used in various fields such as numeral/character displaying
elements, signal lights, light sources for lighting and display devices.
When in use, providing LEDs in packages can provide protection, color
selection, focusing and the like for light emitted by the LEDs.

[0006] A typical LED package includes a base, an LED chip, and an
encapsulating layer. The LED chip is electrically connected to electrical
structures on the base via gold wires. The encapsulating layer
encapsulates the LED chip. Generally, in the process of encapsulating,
the encapsulating layer covers the LED chip by a technique of molding.
However, the LED chip and gold wires are prone to damage during the
process of molding. Thus, a reliability of the LED chip and electrical
connection between the LED chip and the gold wires is impaired. The LED
package has a risk of failing to work due to the damage to the LED chip
or the electrical connection between the LED chip and the gold wires.

[0007] What is needed therefore is a light emitting device package and a
method of packaging a light emitting device which can overcome the above
mentioned limitations.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Many aspects of the present embodiments can be better understood
with reference to the following drawings. The components in the drawings
are not necessarily drawn to scale, the emphasis instead being placed
upon clearly illustrating the principles of the present embodiments.
Moreover, in the drawings, like reference numerals designate
corresponding parts throughout the views.

[0009] FIGS. 1-10 are cross sectional views showing different steps of a
method for forming a light emitting device package obtained by packaging
a light emitting device in accordance with an embodiment of the present
disclosure.

[0010] FIGS. 11-13 are cross sectional views of light emitting device
packages in accordance with different embodiments of the present
disclosure.

DETAILED DESCRIPTION

[0011] Referring to FIG. 10, a light emitting device package in accordance
with an embodiment of the present disclosure is illustrated. The light
emitting device package comprises a base 10, a light emitting element 20
mounted on the base 10, a mask 30 covering the light emitting element 20,
metal wires 40 electrically connecting to the light emitting element 20
and the base 10, an encapsulating layer 50 encapsulating the light
emitting element 20, and a cover layer 60 covering the mask 30 and the
metal wires 40 to protect them from damage or injury.

[0012] The base 10 has a first surface 101 and a second surface 102
opposite to the first surface 101. Two or more through holes 12 are
defined in the base 10 and extend through the first and second surfaces
101, 102. The through holes 12 function as passages to receive the
encapsulating layer 50. The number of the through holes 12 can be altered
according to an actual requirement. The shape of each of the through
holes 12 in a top view can be round, rectangular, etc. . . . The through
holes 12 can be positioned around the light emitting element 20 in a
matrix, or in a circle. Electrical structures 14 are formed on the first
surface 101 around the through holes 12. The electrical structures 14
comprise at least two terminals 141.

[0013] The light emitting element 20 is mounted on the first surface 101
of the base 10, and surrounded by the through holes 12. The light
emitting element 20 can be a light emitting diode (LED), a laser diode
and/or other semiconductor lighting devices which include one or more
semiconductor layers, which may include silicon, silicon carbide, gallium
nitride and/or other semiconductor materials. In the present embodiment,
the light emitting element 20 is an LED. It is understood that, an
ultraviolet, blue and/or green LED may be provided. The light emitting
element 20 has two pads 201 with reverse polarities. In some embodiments,
the pads 201 can form additional shoulders thereon to increase a height
of the pads 201 for conveniently connecting to the metal wires 40. The
pads 201 are positioned at a top surface of the light emitting element
20, that is, the light emitting element 20 is a horizontal structure LED.
It is noted that the light emitting element 20 can be a vertical
structure LED with the two pads 201 positioned on top and bottom surfaces
thereof in an alternative embodiment.

[0014] Also referring to FIG. 3, the mask 30 is arranged on the first
surface 101 of the base 10 and covers the light emitting element 20. A
space 501 is defined between the mask 30 and the first surface 101. The
space 501 is used for receiving the encapsulating layer 50. The mask 30
is made of transparent or translucent material so that light generated by
the light emitting element 20 can transmit through the mask 30. The mask
30 defines two openings 301 therein. The openings 301 correspond to the
pads 201 of the light emitting element 20 respectively for exposing the
pads 201 outside of the mask 30. It is understood that number of the
openings 301 is identical to that of the pads 201 at the top surface of
the light emitting element 20, and if the light emitting element 20 is a
vertical structure LED, the mask 30 defines a single opening 301
corresponding to the pad 201 at the top surface of the light emitting
element 20. The openings 301 can be designed to have such an exact size
that only permits the extension of the pads 201 therethrough. Thus, when
forming the encapsulating layer 50, the liquid encapsulating material can
be prevented from leaking out of the mask 30 via the openings 301 to the
largest extent.

[0015] The metal wires 40 electrically connect the pads 201 of the light
emitting element 20 and the electrical structures 14. The metal wires 40
are positioned outside of the mask 30. Each metal wire 40 connects one of
the pads 201 with one end thereof, and one of the terminals 141 with an
opposite end thereof. The number of the metal wires 40 can be two or more
in this embodiment. It is noted that if the light emitting element 20 is
a vertical structure LED, the number of the metal wires 40 can be one
which connects to the pad 201 at the top surface of the light emitting
element 20, and the pad 201 at the bottom surface of the light emitting
element 20 can connect a corresponding electrical structure 14 directly.

[0016] In some embodiments, a sealing layer 70 can be optionally formed on
the mask 30 to seal the joints of the pads 201 and the metal wires 40.
The sealing layer 70 can increase a joining strength of the metal wires
40 and the pads 201. The sealing layer 70 positioned at the openings 301
can also function as a leak proof structure to prevent the liquid
encapsulating material from leaking from the openings 301 when forming
the encapsulating layer 50. As shown in FIG. 6, the sealing layer 70 can
be divided into multiple ones separated from each other. Each sealing
layer 70 seals a corresponding opening 301. The sealing layer 70 can be
silicone, epoxy or the mixture of the two. The sealing layer 70 can also
contain phosphors therein.

[0017] The encapsulating layer 50 is filled in the space 501 between the
first surface 101 of the base 10 and the mask 30, and encapsulates the
light emitting element 20. The encapsulating layer 50 also seals the
through holes 12 of the base 12. The encapsulating layer 50 contains
phosphors therein. The phosphors may be YAG phosphors, silicon oxynitride
phosphors, or nitride phosphors, etc. The phosphors in the encapsulating
layer 50 can be excited by the light from the light emitting element 20
to emit light with a wave length different from that of the light
generated by the light emitting element 20. The two lights with different
wave lengths combining together can obtain a light with a desired color
such as white.

[0018] The cover layer 60 is arranged on the first surface 101 of the base
10 and shields the mask 30 and the metal wires 40. The cover layer 60 is
made of transparent or translucent material through which light is able
to penetrate. The cover layer 60 may comprise inorganic material such as
silica (SiO2) or titanium dioxide (TiO2).

[0019] The light emitting device package provided by the present
disclosure is characterized in that the encapsulating layer 50 is not in
contact with the metal wires 40. Thus, the damage to the joints of the
metal wires 40 and the light emitting element 20 during the encapsulating
process in the conventional light emitting device package is eliminated
in the light emitting device package provided by the present disclosure.
In addition, the mask 30 can be designed to have such a height that the
encapsulating layer 50 only covers lateral sides of the light emitting
element 20, whereby a damage to the light emitting element 20 during the
encapsulating process can be at least partly decreased.

[0020] Referring to FIG. 11, a light emitting device package in accordance
with an alternative embodiment can further comprise extended layers 142
extending from the electrical structures 14. The extended layers 142 each
connect one of the terminals 141 and extend from the first surface 101 to
the second surface 102 of the base 10. The extended layers 142 are
configured to facilitate subsequent usage or installation of the light
emitting device package.

[0021] Referring to FIG. 12, multiple holes 143 can be defined in the
extended layer 142 corresponding to the through holes 12 of the base 10
respectively. After forming the encapsulating layer 50, the holes 143 are
sealed by soldering material 80.

[0022] Referring to FIG. 13, a light emitting device package in accordance
with an alternative embodiment, in comparison with the embodiment of FIG.
10, can further comprise another sealing layer 90 formed on the second
surface 102 of the base 10. The another sealing layer 90 seals the
through holes 12 of the base 10 to protect the encapsulating layer 50.

[0023] Referring to FIG. 9, a light emitting device package in accordance
with an alternative embodiment, in comparison with the embodiment of FIG.
10, is different in that the encapsulating material 50 in the through
holes 12 of FIG. 10 is replaced by heat conductive material 15 of FIG. 9.
The heat conductive material 15 can be metal, ceramics or other material
having a good heat conductivity. The heat conductive material 15 not only
increase a heat dissipating efficiency of the base 10 but also protect
the encapsulating layer 50 from contamination. The encapsulating material
50 in this embodiment is only filled in the space 501.

[0024] It is understood that features described in the above different
embodiments can be combined or altered without departing from the spirit
of the disclosure. For example, the heat conductive material 15 can be
covered by the extended layer 142 or the another sealing layer 90.

[0025] A method of manufacturing a light emitting device package provided
by the present disclosure now will be described in detail hereinafter
with reference to FIGS. 1-10.

[0026] Referring to FIGS. 1 and 2, a base 10 is provided. The base 10 has
a first surface 101 and a second surface 102 opposite to the first
surface 101. The base 10 has at least two through holes 12 extending
through the first and second surfaces 101, 102. The first surface 101 has
electrical structures 14 formed thereon. The electrical structures 14
comprise at least two terminals 141. A light emitting element 20, for
example, an LED chip, is provided and mounted on the first surface 101 of
the base 10. A bottom surface of the light emitting element 20 is
attached to the first surface 101. The light emitting element 20 has two
pads 201 with reverse polarities at a top surface thereof It is
understood that the through holes 12 can be defined in the base 10 before
or after that the light emitting element 20 is mounted on the base 10.

[0027] Referring to FIG. 3, a mask 30 is brought to cover the first
surface 101 of the base 10. A space 501 is defined between the mask 30
and the first surface 101. The light emitting element 20 is received in
the space 501. All of the through holes 12 of the base 10 are
communicated with the space 501. The mask 30 is made of material with
good light penetration and the light generated by the light emitting
element 20 can penetrate through the mask 30 with little loss. Two
openings 301 are defined in the mask 30 corresponding to the pads 201 of
the light emitting element 20 respectively. The pads 201 are exposed to
an outside of the mask 30 through the openings 301. The openings 301 are
so dimensioned and configured that gaps between the mask 20 and the pads
201 are as small as possible, to thereby prevent liquid encapsulating
material from leaking out of the mask 30 from the openings 301 when
forming the encapsulating layer 50 as disclosed herebelow.

[0028] Referring to FIG. 4, it shows a step of electrically connecting the
pads 201 of the light emitting element 20 and the terminals 141 of the
electrical structures 14 with metal wires 40. The metal wires 40 are
positioned outside of the mask 30. Each of the metal wires 40 has one end
connected to one of the pads 201 and an opposite end connected to one of
the terminals 141.

[0029] Referring to FIG. 5, a sealing layer 70 is positioned on the mask
30 and covers the joints of the pads 201 and the metal wires 40. The
sealing layer 70 is made of material with good light penetration. The
sealing layer 70 functions not only increasing a joining strength of the
pads 201 and the metal wires 40, but also preventing liquid encapsulating
material from leaking from the openings 301. The sealing layer 70 can
also be designed to only cover at the openings 301 to reduce its coverage
whereby shading of the light from the light emitting element 20 caused by
the sealing 70 can be reduced, as shown in FIG. 6.

[0030] Referring to FIG. 7, liquid encapsulating material 51 is injected
in the space 501 from one of the through holes 12 of the base 10, and air
in the space 501 can be exhausted from another through hole 12 as shown
by the arrows. The liquid encapsulating material 51 encapsulates the
light emitting element 20 and forms the encapsulating layer 50 after
solidification. Also referring to FIG. 8, the base 10 can be positioned
upside down during the encapsulating. Thus, the amount of the liquid
encapsulating material 51 can be well controlled to only fill in the
space 501 with the through holes 12 unoccupied.

[0031] Referring to FIG. 9, in one embodiment, heat conductive material 15
can fill in the through holes 12 after forming the encapsulating layer
50. The heat conductive material 15 can be metal, ceramics, etc. . . .

[0032] Referring FIG. 10 again, a cover layer 60 is provided on the first
surface 101 of the base 10 and covers the mask 30 and the metal wires 40.
The cover layer 60 protects the metal wires 40 and the mask 30 from
damage. The cover layer 60 is made of transparent or translucent
material, and comprises inorganic material such as SiO2, TiO2,
etc. . . . The cover layer 60 can be formed to have an inverted U-shaped
configuration defining a space receiving the metal wires 40 and the mask
30 therein, whereby the cover layer 60 does not contact and is separated
from the metal wires 40 and the mask 30.

[0033] Since the encapsulating layer 50 only encapsulates the light
emitting element 20 and is separated from the metal wires 40, the joints
of the light emitting element 20 and the metal wires 40 are prevented
from being impacted by the encapsulating material 51 during the
encapsulating process, whereby a reliability of the light emitting device
package is increased.

[0034] Referring to FIG. 11 again, the electrical structures 14 can extend
from the first surface 101 to the second surface 102 to form an extended
layer 142, after forming the encapsulating layer 50. The extended layer
142 covers the through holes 12 to protect the encapsulating layer 50
from contamination. Also referring to FIG. 12 again, the extended layer
142 can be formed with the electrical structures 14 before the
encapsulating process. For this, when subsequently defining the through
holes 12 in the base 10, holes 143 are also defined in the extended layer
142. After forming the encapsulating layer 50, the holes 143 are sealed
by soldering material 80.

[0035] Referring to FIG. 13 again, another sealing layer 90 can be formed
on the second surface 102 of the base 10 to replace the extended layer
142. The another sealing layer 90 can be made of silicone, epoxy, or the
mixture of the two.

[0036] Further, if the light emitting element 20 is a vertical structure
LED, the mask 30 defines only one opening 301 corresponding to the pad
201 at the top surface of the light emitting element 20. The pad 201 at
the bottom surface of the light emitting element 20 can be directly
connected to one of the terminals 141 of the electrical structures 14.
Other packaging steps for the vertical structure LED are similar to those
of the previous embodiments; thus, a detailed description is omitted.

[0037] It is believed that the present embodiments and their advantages
will be understood from the foregoing description, and it will be
apparent that various changes may be made thereto without departing from
the spirit and scope of the disclosure or sacrificing all of its material
advantages, the examples hereinbefore described merely being preferred or
exemplary embodiments of the disclosure.